saviour stivala wrote: ↑
Wed Mar 03, 2021 7:45 am
Was Yamamoto really talking ‘timing chains stretch’ re RA620H – RA621H?.
There's no timing chain it's timing gears.
Although I'm of the opinion a good chain and tensioner is as good as any gearset up to 14k rpm. Gears are easier to package however.
With a chain you need sprockets, guides, and a tensioner. Timing gears are just sprockets.
That brings up another interesting point, where would a chain be useful in these power units? Maybe the MGU-K to crankshaft? Scavenge pumps? Fuel pump? If there is a pump being driven by the MGU-K it's location would perhaps warrant a chain, or a series of idler gears?
A chain is 3 points of friction, whereas gears is one point of friction, albeit a different type of friction(shear EP type, requiring it's own type of lubrication/additives). Then that begs the question would a chain lower friction and improve efficiency if say you are using 4 or 5 sprockets to run a pump vs two sprockets a chain and a tensioner?
The new API oil specs include chain wear as part of their testing, I sometimes wonder where API gets its ideas from, surely because OE's are putting timing chains in all their engines has something to do with testing requirements. But this is way off topic.
The height of cultivation is really nothing special. It is merely simplicity; the ability to express the utmost with the minimum. Mr.Lee